(1) Field of the Invention
The present invention generally relates to a head supporting device of a magnetic disk system, and more particularly to a device for supporting a magnetic head in a magnetic disk system so as to position the magnetic head with high positioning accuracy.
(2) Description of the Prior art
Recently, a magnetic disk containing a large quantity of information at a high packing density has become popular and been widely used for recording and reproducing information. In order to easily and safely use such a magnetic disk, it is necessary that a magnetic head be positioned with high accuracy in a magnetic disk system in a manufacturing stage of the magnetic disk system. The magnetic head of the magnetic disk system has a surface which slides on a magnetic disk (which is inserted by a user into the system). This magnetic head is a dual-surface type head, the magnetic head having an upper magnetic head with a surface positionable on a front-side surface of the magnetic disk, and having a lower magnetic head with a surface positionable on a reverse-side surface of the magnetic disk. The upper magnetic head is mounted on an arm member of the system, and the lower magnetic head is mounted on a carriage member of the system. In this magnetic disk system, it is necessary to support the upper and lower magnetic heads by means of an appropriate head supporting device so as to be able to position the heads with high accuracy.
Thus, when the magnetic disk system is manufactured, it is desirable that an upper gimbal to which the upper magnetic head is attached be mounted on the arm member and accurately fixed by an adhesive agent at a prescribed position, and that a lower gimbal to which the lower magnetic head is attached be mounted on the carriage member and accurately fixed by an adhesive agent at a prescribed position. It is also desirable that, after the gimbals are temporarily fixed to the carriage and the arm, no positional deviation of the gimbals from the prescribed positions occurs due to the temporary fixing of the gimbals by the adhesive agent at the prescribed positions and due to changes in the ambient temperature in the surrounding environment, thus allowing the upper and lower magnetic heads in the magnetic disk system to be positioned with high accuracy. The above mentioned deviation is detrimental to accurate positioning of the magnetic heads of the magnetic disk system.
Conventionally, there is a magnetic head supporting device which incorporates an improved fixing method so as to meet the above described requirements. For example, Japanese Laid-Open Patent Publication No.61-246973 discloses such a fixing method which is applicable to a magnetic disk system. The disclosed method includes a first fixing step and a second fixing step. In the first fixing step, a lower gimbal is temporarily fixed to a carriage at a given position by applying a first adhesive agent, and an upper gimbal is temporarily fixed to an arm at a given position by applying the first adhesive agent. The first adhesive agent used is capable of being cured in a very short time.
The carriage or the arm is formed with an adhesion surface to which an adhesive agent is applied so as to fix the carriage or the arm to the lower or upper gimbal by the adhesive agent. The carriage or the arm is also formed so as to have an inlet opening into which an adhesive agent is injected, and a number of grooves connecting the inlet opening to the adhesion surface. In the second fixing step, a second adhesive agent (e.g., an epoxy based adhesive) requiring a relatively long time to be cured is heated so as to decrease its viscosity, and the second adhesive agent is then injected into each inlet opening to spread over the adhesion surface so as to fix the gimbals to the carriage and to the arm.
However, it is difficult for an adhesive agent to evenly spread over each surface of the upper and lower gimbals because the carriage and the lower gimbal, as well as the arm and the upper gimbal, have an extremely flat surface therebetween and when the two surfaces are attached together they show a relatively high adherence. Thus, in the case of the above described prior art, there is a problem in that the first adhesive agent for temporary fixing the gimbals does not evenly spread over the surfaces of the upper and lower gimbals, partially because, if the amount of the adhesive agent is insufficient, a necessary adherence strength is not produced, and partially because, if the amount of the agent is excessive, a relatively long curing time is required in the manufacturing process. The excessive amount of the first adhesive agent cannot be cured sufficiently, thereby the workability of the system in the manufacturing process deteriorates. Thus, the upper and lower gimbals temporarily fixed by the first adhesive agent occasionally deviate from their given positions due to the amount of the first adhesive agent being too small and due to the agent being insufficiently cured.
The above mentioned grooves perform the second fixing step in which the second adhesive agent is injected into the inlet openings to spread over the adhesion surfaces of the carriage and the arm. Generally, a viscosity of the second adhesive agent such as an epoxy based adhesive is higher than a viscosity of the first adhesive agent used for the temporary fixing of the gimbles. Also, even when heated, the viscosity of the second adhesive agent is not easily lowered to a level low enough to allow the second adhesive agent to evenly spread over the adhesion surfaces. Thus, if the above grooves have a fluid passage with a relatively large sectional area, the second adhesive agent does not easily flow through the grooves into the adhesion surfaces in the second fixing step. For example, in the above described prior art, each of the grooves is 0.5 mm wide and 0.1 mm deep.
Moreover, to fix the lower gimbal to the carriage and the upper gimbal to the arm in the second fixing step, a relatively large amount of the second adhesive agent is needed because the grooves formed in the carriage or the arm have a relatively large sectional area. Thus, there is a problem in that the second adhesive agent needs a relatively long time to be cured and additional time is necessary in the manufacturing process of the magnetic disk system.